Directional signal radiation system



Oct. 20, 1964 B. P. wAsHBURNE DIREcTIoNAI. SIGNAL RADIATION SYSTEM Filed April 26. 1961 United States Patent() 3,153,788 DlRECTlNAL SEGNAL RADIATIN SYSTEM Brenton l?. Washhurne, Penn Valley, Pa., assignor, by mesne assignments, to Philco Corporation, Philadelphia, Pa., a corporation of Delaware Filed Apr. 26, 1961, Ser. No. 195,748 9 Claims. (Cl. 343-106) This invention relates to directional radiation of highfrequency signals and more particularly to directional radiation of a signal from a stationary antenna array.

It is well known that directional radiation of a highfrequency signal from a stationary antenna array can be achieved by applying the signal in different phases to antenna elements of the array. In radar, for example, such directional radiation, sometimes referred to as electronically steering a beam, has superseded the method which involved mechanical movement of a beamradiating antenna. The phased array method is known to be superior in various ways to the mechanical method.

In the phased-array method, accuracy of phase control is an important factor. For example, for accurate beaming of the signal in a given direction from a planer array, it is necessary that the antenna elements in each row or column of the antenna array be phased in exact relation to one another. More particularly, there must be a certain phase difference in the signal supplied to the successive antenna elements. Prior phasing arrangements have not been entirely satisfactory from the standpoint of assured accuracy, and moreover they have been cornplex and expensive.

Ane object of the present invention is to provide an improved phasing arrangement in a phased-array system which provides the desired accuracy.

Another object of the invention is to provide an improved phasing arrangement which is relatively simple and inexpensive.

Other objects and features of the invention will be apparent as the description proceeds.

In the phasing arrangement according to this invention, there are successive phasing stages and the phasing operation is effected by three signals-namely, a first signal of predetermined frequency whose phase is to be shifted, a second signal of different frequency, and a third signal of the same frequency as said second signal but differing therefrom in phase by a phase angle which represents the phase shift to be produced in each of the successive phasing stages.

In the preferred form of the system as hereinafter described, each of the phasing stages includes a pair of serially-connected mixers. The first signal is supplied to the first mixed of the rst phasing stage; the second signal is supplied to the first mixer of each phasing stage; and the third signal is supplied to the second mixer of each phasing stage. Since in this system a single signal (the third signal) serves to establish the phase shift in each of the phasing stages, there is a constant phase shift from stage to stage.

The invention may be fully understood from the following detailed description with reference to the accompanying drawing in which the single figure is a block diagram of a phasing arrangement according to this invention.

Referring more particularly to the drawing, there are represented three antenna elements 10, 11 and 12 of a row or column of elements in a planar antenna array. While only three such elements are shown, it Will be understood that the row or column may comprise any number of elements. For the purpose of disclosure of the present invention, the three elements shown will suce.

In order to direct the beamed signal in a given direction it is necessary that the signal be supplied to the lice successive antenna elements in different phases which differ from element to element by a predetermined angle which may be designated rp. Suppose, for example, that the signal whose phase is to be shifted has a frequency JA so that this signal may be designated oc. This signal is to 'be supplied in different phases to the antenna elements 10, 11 and 12, either at the frequency fA or at a different frequency obtained by conversion.

At 13 there is represented a source of the signal fA. For simplicity, it is assumed that this signal is to be supplied without frequency conversion to the antenna elements. Accordingly this signal is supplied directly to antenna element 10. It is also supplied to mixer 14 of the first phasing stage which is represented by the rst broken line rectangle. At 15 there is represented a source of a phasing signal which has a frequency fB different from that of signal iA. The phase of signal fB may be designated This signal is also supplied to mixer 14. In the system illustrated the difference signal (iA-f3), having a phase angle (et-), is derived from mixer 14 via a filter and an amplifier represented at 16 and is supplied to a second mixer 17. Signal fB is also supplied to a phase shifter 18 which shifts its phase by the angle g5, e.g., to (-l-tp). The phase-shifted signal is also supplied to mixer 17. This sum of the two signals supplied to mixer 17 is signal fA with a phase angle (ot-hp), which is derived via a filter and an amplifier represented at 19 and is supplied yto antenna element 11. This completes the phasing operation in the first phasing stage.

The signal fA with phase angle (a4-) is also supplied to mixer 20 to which the signal fB with phase angle is also supplied. The difference signal (fA-B) with phase angle (ot-i--) is derived via a filter and an amplifier represented at 21. This signal is supplied to mixer 22 to which the signal fB with phase angle (-l-gb) is also supplied. The sum of the signals supplied to mixer 22 is signal jA with phase tangle (ot-l-Zo). This signal is derived via a ilter and an amplifier represented at 23 and is supplied to antenna element 12. This completes the phasing operation in the second phasing stage represented by the second broken line rectangle.

Each of the succeeding phasing stages (not shown) is similar to those described, and the phasing operation is the same in each stage. Thus the third stage provides the signal fA with a phase angle (vH-3p) which is supplied to the next antenna element; the fourth stage provides signal fA with phase angle (Orl-495) which is supplied to the next antenna element; and so on.

From the foregoing description it will be seen that in the phasing system of this invention as illustrated there is a pair of serially-connected mixers in each phasing stage, and a single phase shifter serves cooperatively with the mixers to effect the phasing operation in each of the phasing stages comprising the pairs of mixers. By adjusting 'the phase shifter to change the phase angle qb, the direction of radiation can be changed at will. Thus in a scanning nadar system the phase shifter may be continuously adjusted either manually or automatically to change the phase angle tp, so as to cause scanning motion of the beam. The phase shifter may, of course, be of any suitable forrn. For example, it could be a simple delay line.

Since in this system the phase shift from element to element ofthe antenna array is eifected by means of a `single phase shifter, the antenna elements are vphased in exact relation to one another. Thus the system achieves the Ydesired accurate phasing which is necessary for .accurate directional radiation ofthe beam. Moreover the system is relatively simple and is therefore relative inexpensive.

In the system as illustrated, in each phasing stage a difference signal is derived from the lirst mixer and a sum signal is derived from the second mixer. However it Will 3 be apparent that this order could be reversed, in which case the phases of the antenna elements following the first element would be (ot-p), (ot-2gb), etc. It Will also be apparent that the phase shifter 1S may produce the signal fB with the phase (f3-rp).

For simplicity it was assumed that the signal fA With appropriate phase shifts is supplied directly to the antenna elements. However this signal may be converted to a different frequency, e.g., a higher frequency, before it is supplied to the antenna elements. This simply involves the provision of frequency converters in the connections extending to the antenna elements. Of course this does not affect the phasing operation.

While the invention has been illustrated and described with reference to a single embodiment, it will be understood that the invention is not limited thereto but contemplates such modifications and further embodiments as may occur to those skilled in the art.

I claim:

l. In a system for directional radiation of a high-frequency signal from an antenna array, a phasing arrangement comprising successive pairs of serially-connected mixers, means for supplying a first signal of predetermined frequency to the first mixer, means for supplying a second signal of different frequency .to the rst mixer of each pair of mixers, means for producing from said second signal a third signal of the same frequency but of different phase, and means for supplying said third signal to the second mixer of each pair of mixers.

2. In a system for directional radiation of a high-frequency signal from an antenna array, a phasing arrangement comprising successive pairs of serially-connected mixers, means for supplying a first signal of predetermined frequency to the first mixer, means for supplying a second signal of different frequency to the first mixer of each pair of mixers, phase shifting means common to said pairs of mixers, means for supplying said second signal to said phase shifting means to produce a third signal of the same frequency but of different phase, and means for supplying said third signal to the second mixer of each pair of mixers.

3. In a system for directional radiation of a high-frequency signal from an antenna array, a series of antenna elements, a series of mixers comprising successive pairs, means connecting the pairs of mixers between consecutive pairs of said elements, means for supplying said signal to the first antenna element and to the first mixer, means for supplying a second high-frequency signal of different frequency to the first mixer of each pair of mixers, means for producing from said second signal a third signal of the same frequency but of different phase, and means for supplying said third signal to the second mixer of each pair of mixers.

4. In a system for directional radiation of a high-frequency signal from an antenna array, a phasing arrangement comprising a plurality of successive phasing stages each including a pair of serially-connected mixers, a source of a signal having a predetermined frequency, means connecting said source to the first mixer of the first phasing stage, a source of a phasing signal having a different frequency, means connecting the latter source to the first mixer of each of said phasing stages, `a single phase shifter connected to the latter source, and means for supplying the output of said phase shifter to the second mixer of each of said phasing stages.

5. In a system for directional radiation of a high-frequency signal from an antenna array, a phasing arrangement comprising a source of a first signal of predetermined frequency, means providing second and third signals having a frequency different from that of said first signal and differing from each other in phase by a phase angle qa, and means comprising a plurality of successive phasing stages for producing in response to said three signals a plurality of signals having the same frequency as said first signal and differing progressively in phase by the phase angle qb, each of said phasing stages including a pair of serially-connected mixers to Which said second and third signals are applied respectively.

6. In a system for directional radiation of a high-frequency signal from an antenna array, a phasing arrangement comprising a source of a first signal having a frequency A and a phase a, a source of a second signal having a frequency fB and a phase means for producing from said second signal a third signal having the frequency fB and a phase (-i-p), and means comprising a plurality of successive phasing stages for producing in response to said three signals `a plurality of signals having the frequency fA and having respective phases which differ progressively by the phase angle qb, each of said phasing stages including a pair of mixers to which said second and third signals are applied respectively.

7. ln a system for directional radiation from a multielement antenna array wherein it is desired to supply -a signal to one antenna element and the same signal with predetermined phase shift to the next antenna element, a first mixer, means for supplying said signal to one antenna element and to said mixer, means for supplying to said mixer a second signal having a fixed frequency different from that of said first signal, a second mixer, means for supplying an output from said first mixer to said second mixer, means for producing from said second signal a third signal of the same frequency but shifted in phase, means for supplying said third signal to said second mixer to derive said first signal with its phase shifted in correspondence to the phase shift of said third signal, and means for supplying the phase-shifted first signal to the next antenna element.

8. In a system for directional radiation of a high-frequency signal from an antenna array, means providing a first signal of predetermined frequency, means providing second and third signals having a frequency different from that of Vsaid rst signal and differing from each other in phase by a phase angle 4:, a first phasing stage supplied with said three signals for producing a fourth signal having the same frequency as said first signal but differing therefrom in phase by the phase angle 4), and a second phasing stage supplied with said second, third and fourth signals for producing a fifth signal having the same frequency as said first signal but differing therefrom in phase bythe phase angle 2p.

9. In a system for directional radiation of a high-frequency signal from an antenna array, means providing a first signal of predetermined frequency, means providing a second signal having a frequency different from that of said first signal, phase shifting means supplied with said second signal to produce a third signal diering from said second signal in phase by a phase angle qb, a first phasing stage supplied with said three signals for producing a fourth signal having the same frequency as said first signal but differing therefrom in phase by the phase angle 11, and

a second phasing stage supplied with said second, third fand fourth signals for producings a fifth signal having the same frequency as said first signal but differing therefrom in phase by the phase angle 21p.

References Cited in the file of this patent UNITED STATES PATENTS 3,005,960 Levenson Oct. 24, 1961 

7. IN A SYSTEM FOR DIRECTIONAL RADIATION FROM A MULTIELEMENT ANTENNA ARRAY WHEREIN IT IS DESIRED TO SUPPLY A SIGNAL TO ONE ANTENNA ELEMENT AND THE SAME SIGNAL WITH PREDETERMINED PHASE SHIFT TO THE NEXT ANTENNA ELEMENT, A FIRST MIXER, MEANS FOR SUPPLYING SAID SIGNAL TO ONE ANTENNA ELEMENT AND TO SAID MIXER, MEANS FOR SUPPLYING TO SAID MIXER A SECOND SIGNAL HAVING A FIXED FREQUENCY DIFFERENT FROM THAT OF SAID FIRST SIGNAL, A SECOND MIXER, MEANS FOR SUPPLYING AN OUTPUT FROM SAID FIRST MIXER TO SAID SECOND MIXER, MEANS FOR PRODUCING FROM SAID SECOND SIGNAL A THIRD SIGNAL OF THE SAME FREQUENCY BUT SHIFTED IN PHASE, MEANS FOR SUPPLYING SAID THIRD SIGNAL TO SAID SECOND MIXER TO DERIVE SAID FIRST SIGNAL WITH ITS PHASE SHIFTED IN CORRESPONDENCE TO THE PHASE SHIFT OF SAID THIRD SIGNAL, AND MEANS FOR SUPPLYING THE PHASE-SHIFTED FIRST SIGNAL TO THE NEXT ANTENNA ELEMENT. 